Abstract: A wire thermal spray gun such as a two-wire arc gun has a speed regulator for a DC pull motor in the gun. Armature current corresponds to pulling torque on the pull motor depending on load resistance of the wires. A DC push motor is between a wire supply and the gun, with wire conduits connecting to the gun. A controller provides the push motor with a controlled pushing torque. Feedback of the armature current of the pull motor to the controller adjusts the pushing torque in direct response to change in the pulling torque, such that load sharing is maintained between the push motor and the pull motor.

Abstract: A powder injection apparatus for a plasma spray gun includes a block having channelling therein for liquid coolant. A powder port extends through the block in proximity to the channelling so as to be cooled by coolant flowing therein. The port has a powder inlet receptive of spray powder in a carrier gas, and has a powder outlet end formed as a tubular protrusion extending from the block. A pair of extensions extend from the block proximate the protrusion on diametrically opposite sides thereof. Each extension has at least one orifice therein disposed so as to direct gas onto the protrusion. A pair of additional gas exit openings direct gas to the face of the gun.

Abstract: A gas cap for a thermal spray gun has a passage therethrough including an entrance channel, an exit channel, and an intermediate channel connecting between the entrance and exit channels. The entrance channel is cylindrical on an entrance axis, and the exit channel is convergingly conical on an exit axis oriented at 45.degree. to the entrance axis. The intermediate channel is symmetrical to the plane of the entrance and exit axes and has a near portion and a far portion. The near portion is semicylindrical about the entrance axis, and the far portion is semicylindrical about a far axis segment lying in the plane. That segment is offset from the entrance axis away from the exit end of the gas cap, and is oriented at 14.degree. to the entrance axis, the three axes intersecting at a common point.

Abstract: An arc spray gun has a generally frusto-conical head member of electrically insulating material, with the small end facing forwardly in the direction of spray. Wire is fed through a pair of electrically conductive tubular wire guides containing pressure contact means that extend through the head member and converge to contact the wire ends for arc formation and melting of the metal. A gas jet nozzle provides compressed gas for atomization and spraying of the molten metal. A first gas cap is disposed coaxially on the head with rear and forward gas seals so as to define an annular gas chamber. A secondary gas is supplied to the annular chamber, and the first gas cap has a pair of diametrically opposite orifices therein for directing the secondary gas from the chamber to modify the molten metal spray in a fan shape. The orifice may have elongated cross sections to produce a rough coating surface if desired.

Abstract: A heavy duty plasma spray gun for extended industrial service is disclosed. The gun includes a gas distribution member made of a material having a coefficient of expansion different from that of the parts surrounding it. The gas distribution member is forcibly urged by a resilient member such as a coiled spring against a seal so as to assure the plasma gas is introduced into the gun arc in a manner only defined by the gas distribution member. The gun has liquid cooling for the nozzle (anode) and the cathode. Double seals are provided between the coolant and the arc region and a vent is provided between the seals which provides an indication when a seal has failed. Some parts of the gun are electrically isolated from others by an intermediate member which is formed as a sandwich of two rigid metal face pieces and an insulator disposed between them. The metal face pieces provide a rigid body to attach the remaining parts in proper alignment therewith.